Parallell-Plate Electron Multipliers

A review is given of the properties of parallel plate electron multipliers and present development work is described. In particular the type of multiplier fabricated by RF-sputtering of separate potential divider and secondary emission layers is discussed. This allows optimization of the two functions. Typical plate dimensions are 2O×2O mm, with a separation of ¿ 0.3 mm. The theories for the straight pipe-shaped multiplier and the parallel plate multipliers are discussed and a comparison is made with measurements, The influence of the geometry is discussed, including optimum plate spacing. A difference compared with tubular multipliers is that electron avalanches spread sideways, because of statistics and electric repulsion effects. Studies of pulse shapes and timing properties are reported. Current pulses at the oultput are about 10 nsec long, for each electron avalanche, Severlal superimposed avalanches caused by ionic feedback build up the integrated voltage pulse to a length of a few tenths of a ¿sec.